1. Field of the Invention
The present invention relates to a control value output apparatus for controlling an output of, e.g., tone volume by a movable operation member such as a slider provided to a slide volume member.
2. Description of the Prior Art
In electronic equipment such as audio and video equipment (e.g., an electronic musical instrument), a slide volume member 1 is often arranged on an operation panel, as shown in FIG. 6.
The slide volume member 1 is used to control an output such as a tone volume within a predetermined range (a range of 0 to 127 in FIG. 6) by reciprocating a "slider" 2 along a slit 3 to adjust a variable resistor arranged in the slide volume member 1 in accordance with the position of the slider 2. In addition to the tone volume member, outputs to be controlled by the slide volume 1 include a tempo of a music piece, an interval, a tone color, and the like in audio equipment, and luminance, contrast, and the like of a screen in a video equipment.
As shown in FIG. 6, operation buttons 4 and 5 for incrementing/decrementing the same output, step by step a are often arranged on the operation panel on which the slide volume member 1 is arranged. Once the operation button 4 or 5 is depressed, for example, a presently output tone volume is incremented/decremented by one step. When the button is continuously depressed, the tone volume is continuously incremented/decremented.
In an electronic musical instrument, an output such as tone volume is controlled on the basis of, e.g., tone volume data included in preset data or tone data such as auto-accompaniment tone data regardless of the position of the slider 2.
When one output value can be independently changed by the slide volume member 1 and other operation members 4 and 5, or another control element such as setup data like in the above-mentioned prior art, the following problems are posed.
FIGS. 5A and 5B exemplify tone volume as an output, and show the movement of the slider 2 of the slide volume member 1, and variations of the tone volume. Assume that the slider 2 is held at a position of a volume value "40" from time t.sub.0 to time t.sub.3, as shown in FIG. 5A. As shown in FIG. 5B, tone volume of the volume value "40" is output in accordance with the position of the slider 2 from time t.sub.0 to time t.sub.1. During a time interval between time t.sub.1 and time t.sub.2, the incremental operation button 4 (FIG. 6) is continuously depressed to increase the tone volume up to a volume value "80", and the tone volume of the volume value "80" is held until time t.sub.3. In this case, when the slider 2 is operated at time t.sub.3, and is moved from the position of the volume value "40" in a direction to increase the value, the tone volume of the volume value "80" output so far is temporarily and instantaneously decreased to the volume value "40" corresponding to the held position of the slider 2, and then begins to be increased from the value "40" in accordance with the movement of the slider 2.
In contrast to this, when the decremental operation button 5 is continuously depressed to set the volume value "80" in a state wherein the slider 2 is located at a position indicating a value larger than the volume value "80", and the slider 2 is moved in a direction to decrease the value, the volume value of the tone volume is temporarily instantaneously increased up to a value corresponding to the position at the beginning of the movement of the slider 2.
As described above, when one volume value is to be independently controlled by the slider 2 of the slide volume member 1, and other volume control elements such as incremental/decremental operation buttons 4 and 5, a tone is abruptly changed at an instance when the slider 2 is moved, resulting in aurally unnatural sound.
Since the slide volume member 1 is mechanically arranged, the slider 2 is often unexpectedly moved by, e.g., a vibration, and in this case, the output is also abruptly changed.